Optical projection system



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v 2,510,080 orricsr. PRQJECTION SYSTEM l s me *m Lawrence J. Cuneo, United States Navy' y Application March 1s, 194e, serial No. 655,361

4 Claims. (CL 88-24) (Granted under the act o March 3, 1883, as IV amended April 30, 1928; 370 0. G. 7527 The present invention relates to optical systems. and particularly to an improved lens system having an extremely wide neld of View Without sacrice of quality of denition or of lens speed. In tl e form of lthe invention shown in the drawings, the principles of the invention are iBustrated in a prei-erred icrrn for use as a proie tion system, and the arrangement disclose-:i perni-i projection of asharp, brilliant motion-picture image cn an extremely wideangle screen.

Projection systems ofthis general type can be utilized for various purposes, but are particularly suitable for use in synthetic antiair craft or aerial gunnery trainers, so4 that a student can be given rapid and effective instruction in the elements of gunnery by training a mockup weapon on moving-picture images of attacking planes. Naturally, since a crew handling a real v gun can expect to repel an attack from almost it is of great advantage to be an unusually wide eld of View,

any direction, able to utilize so that the .student will learn to handle his weapons efectively against any possible type of attack. At thesame time, the quality of definiticnof the lens system must be good enough so that tiny images of'distant planes can be recognized as friendly or enemy types, and the illumination ofthe screen should be sufficient to permit use of photoelectric scoring devices as.

well as to provide snisractory illumination for sighting the synthetic weapons o the trainer.

t-is the object of this invention to provide e wide-angle optical-system meeting these reqnirenients and adapted for use in any appli- -c'a'fson requiring a relatively fast lens system v capable o good denition throughout a Wide rielo "oyiefV i l As shown, the system is arranged to project aco. image from a single motion-picture lm to a quadrantor a spherical dome, so that the field or' view extends through 180v degrees in azimuth and 9 0 degrees in elevation.v The result is acf compl'ished "oy the novel combination of a pro-. 1

jection lens having a definite curvature ofl field: :together with a mirror having a eld of equal #and oppositeV curvature so that they cc-:nf pensate for each other and permit sheryiocu's-` etal on the'screen.' I If desired, the lens and mirror combination can'he'augmented-by' -type of lens is ideally' suited.

-. The function of the lens system 3 is Awhich generally corresponds in shape and loca'A overall Petzyal curralzure becomes zero.

:the entire eld and ya t permits a lens-.speed un.' '1 to FX2 with the arrangement shown.

'Y'jshen Vthe lens ani mirror-*are exactly matched to Vthe" lens pei-Use, both `the lens-system and the provision of mirrors so that none of the projection equipment need be positioned in the center of the spherical screen. This feature is not vessential to the practice of the invention, but

aords fin-ther advantages in that it permits an observer or student to man a gun turret or other l' 1nock-up weapon at the exact geometric center o1 the screen. y

y In the drawings:

Fig. l is a` diagrammatic illustration of an optical system in accordance with the teachings of this disclosure. l

Eig. 2 is a similar View of a modcation of the system shown in Fig. l, to permit an 0bserverV to view the screen from its exact center. Fig. 3 is a perspective illustration of the sys.- tein shown in Fig. 2.

The screen lu is shown as of semi-spherical shape, comprising a quadrant of a complete sphere, but it need not necessarily be exactly spherical in shape, and reasonably good results can be obtained by projecting an image on any three-dimensional screen, such as the interior walls of any ordinary room. The image is projected from a point l2 through a lens system generally indicated at i3 to a concave spherical mirror i4 and thence to the screen iD. Obviously, the image will normally be projected 'l from a motion-picture projector having a. nlm l5, a source of illumination I6 and condensing lenses l. (SeeFie;ure2.) This image projected through the lens system i3 vis characterized by a dennis(` positive curvature'-H of field. For this prpose the Petzral portrait` to focus an image in a positively curved field t9, Fig. ,L 1

tion to the negatively cnrved field of focus I9 'of thev concave spherical mirrorjl so thatjthe"v combination gives a high 'quality'of image over.

'It v follows that the' nest results are" obtained' 4and while the present application makes nofclaim',

mirror vare and described to` permit a thorough appreciation and understanding ofthe' general optical system.

The lens, system i3 consists of six separa-te elements, designated as A to F inclusive. The speelcations of the lens elements,` and the mirror are as follows: 1

' ihiclc'ness Element Glass and Index of Refraction Radius and Separation A' Dense Barium Crown* 3.894 0.237 Sodium LSIlOO-new 58.8.. 1. 7 (l. O07 B Sarno +3. 633 O. 236 5. 138 0. l5 C Exim Dense l`lint.... -2 2:72 0.10.1

Sodium 1.64900 new 33.8 +24. g Same 4. D +4. 499 0. 000 E Boro Silicate Crown.-- +4.499 0. 50g 1.51700 ne'v 64.5 -2 h5 0.001l l" Barium Flint.. Q. 295

1.50560 new 43.6 l .13o 14 Front surfaced Mirror--- 9. 265 2 144 2 To mirror.

= To screen.

It may be of advantage for the observeror student to be located at the geometric center of the screen. This can be accomplished without interference with the projection system by the arrangement shown in Figures 2 and 3. Here a rerays do not cross the center of the screen i9 which is occupied by the observer. Thus the obv server may be positioned at the most desrltie of the system.

The present invention permits projection of images on an unusually wide eld of view and eliminates the necessity for resorting to batteries a positively curved eld oifocusya concave spherical mirror positioned with its field. of focus substantially coincident with' the field of the lprojection lens, a three-dimensional screen, amiA at least one mirror to re-ect light rays from the projection lens to the spherical mirror without passing said rays through-the geometric center V' point of the screen.

2. In an optical projection system, the com? bination comprising a motion-picture 'projector including a. lens, a three-dimensional concave screen, an observation position located with re eld of focus of the projector lens, the reileotor l being also positioned to reflect ar; f nage from the projector onto the screen distribi ted over the area thereof. l

' ector system is provided, which comprises a pair f of plane mirrors 2l and 22 to redirect the light -no point without interfering with the functioning.

of synchronized projectors or other elaborate and expensive installations to accomplish satisfactory image projection on a large three-dimensional screen. The system also possesses marked advantages by reason of the fact that the rays reaching the screen are almost parallel, giving a great depth of focus. Moreover, these resultsare accomplished without the use of delicate or cumbersome equipment, and the system is of such inherently simple design as to be readily adapted to other types of apparatus requiring wide-angle of the invention as claims.

The invention, if patented, may oe manufa numerous modiications and variations and therefore I wish to be limited only by the scope dened in the appended turedand used by or for the Governmentior governmental purposes Without Having thus described the invention, what the payment tov me of anyroyalty thereon. y 1

le of this patent:

UNITED STATES PATENTS Number Name l Date 545,422 Chase Aug. 27, 1895 1,412,997 Bonneau et al Apr. 18, 1922 1,419,901 Lehnho et al June 13, 1922 1,551,259 Merriman Aug. 25, 1925 1,797,202 Warmisham Mar. 17, 1931 1,831,939 White Nov. 17, 1931 1,919,561 Kogel July 25, 1933 2,039,878 Boykow May 5, 1936 2.045,12() Carpenter June 23, 1936 2,074,991 Salcedo Mar, 23, 1937 2,084,795 Donlc Junev 22, 1937 1 2,146,905 McLeod et al Feb. 14, 1939 2,174,778 Croft Oct. 3 1939 2,211,219 .j Serrurier Aug. 13, 19401' 2,215,512 1 Fetter Oct. 1,' 1940 2,306,679 Warmisham Ded 29, 19712'r 1 FOREIGN P A".Pflltlls A .''f .Number f f' Country 'Date' .Y coincident therewith.

desire to secureby Letters 2"* 3. In an optical system as defined in claim 2, v 1

the projector lens being a Petzval portrait type.

4. `In an optical projection system, the oom- Y tioned to reilect images from the projector to 'l the screen distributed over the area thereof, the path of the reection being away from the observation position, the reector system including a mirror with a field of focus corresponding with the field of focus of the projector lens and located LAWRENCE J. CUNEO.

REFERENCES CITED The following references are of record in the' y' 

